This chapter traces the history of the science of Italian administrative law from the beginning of the nineteenth century to the present day, highlighting how, in Italy, administrative law has for a very long time been the most important branch of administrative studies. In the Italian legal system, administrative law first established itself as a leading element in the construction of the administrative state (in particular, between the end of the nineteenth century and the beginning of the twentieth century), and then gradually opened up, especially in the second half of the twentieth century, to the influences of the science of administration and the other social sciences that study public administration.